Method And Apparatus For Tool Retrieval

Abstract

The present disclosure is directed towards, in general, retrieval tools operable for conveyance within a wellbore extending below a wellsite surface, and methods of using such retrieval tools. One such retrieval tool comprises an annular member operable to receive a conveyance terminating at a downhole tool lodged within the wellbore. The annular member may subsequently receive and engage a portion of the downhole tool. The retrieval tool also comprises a flapper selectively operable to sever the conveyance if the downhole tool cannot be dislodged from the wellbore.

What is claimed is: 
     
         1 . A method, comprising:
 conveying a retrieval tool along a conveyance within a wellbore extending into a subterranean formation;   utilizing the retrieval tool in an attempt to engage and retrieve a downhole tool in the wellbore; and   severing the conveyance with the retrieval tool downhole upon failure of the attempt.   
     
     
         2 . The method of  claim 1  wherein conveying the retrieval tool along the conveyance comprises conveying the retrieval tool on a pipe string to which the retrieval tool is coupled. 
     
     
         3 . The method of  claim 2  wherein conveying the retrieval tool along the conveyance comprises sliding the retrieval tool and the pipe string over the conveyance. 
     
     
         4 . The method of  claim 1  wherein the conveyance comprises a cable extending between the downhole tool and a well-site surface from which the wellbore extends. 
     
     
         5 . The method of  claim 4  wherein the cable comprises at least one of a wireline and a slickline. 
     
     
         6 . The method of  claim 1  wherein the conveyance comprises coiled tubing extending between the downhole tool and a well-site surface from which the wellbore extends. 
     
     
         7 . The method of  claim 1  wherein severing the conveyance with the retrieval tool comprises selectively operating a flapper assembly of the retrieval tool. 
     
     
         8 . The method of  claim 7  wherein conveying the retrieval tool along the conveyance within the wellbore comprises passing the conveyance through the flapper assembly. 
     
     
         9 . The method of  claim 8  wherein severing the conveyance with the retrieval tool comprises closing the flapper on the conveyance with sufficient force to sever the conveyance. 
     
     
         10 . The method of  claim 9  wherein closing the flapper comprises pumping fluid down the wellbore from a well-site surface from which the wellbore extends. 
     
     
         11 . The method of  claim 10  wherein the flapper is mechanically biased towards an open position, and wherein pumping fluid down the wellbore from the well-site surface comprises pumping the fluid at a rate sufficient for the fluid to overcome the mechanical bias and urge the flapper away from the open position. 
     
     
         12 . An apparatus, comprising:
 a retrieval tool operable for conveyance within a wellbore extending below a wellsite surface,
 wherein the retrieval tool comprises:
 an annular member operable to receive a conveyance terminating at a downhole tool lodged within the wellbore, and then receive and engage a portion of the downhole tool; and 
 a flapper operable to sever the conveyance. 
 
   
     
     
         13 . The apparatus of  claim 12  wherein the flapper is biased towards an open position permitting passage of the conveyance. 
     
     
         14 . The apparatus of  claim 12  wherein the wellbore comprises a substantially non-vertical section. 
     
     
         15 . The apparatus of  claim 12  wherein the conveyance comprises a cable extending between the wellsite surface and the downhole tool. 
     
     
         16 . The apparatus of  claim 12  wherein the conveyance comprises coiled tubing extending between the wellsite surface and the downhole tool. 
     
     
         17 . An apparatus, comprising:
 a fishing string operable for conveyance within a wellbore extending below a wellsite surface,
 wherein the fishing string comprises:
 a mule shoe operable to receive a conveyance terminating at a downhole tool lodged within the wellbore, and then to receive a portion of the downhole tool; 
 an overshot operable to receive the conveyance, and then to receive and engage a portion of the downhole tool; and 
 a flapper assembly operable to sever the conveyance. 
 
   
     
     
         18 . The apparatus of  claim 17  wherein the flapper assembly is biased towards a position permitting passage of the conveyance therein. 
     
     
         19 . The apparatus of  claim 17  wherein the conveyance comprises a cable extending between the wellsite surface and the downhole tool. 
     
     
         20 . The apparatus of  claim 17  wherein the conveyance comprises coiled tubing extending between the wellsite surface and the downhole tool.